Inner tube and its method of manufacture



Jan. a; 192s. Y I l 1,521,879.

J. E. GLlcKsRfp mman TUBE Annlr's METHOD oF mnumcsuni: Filed Nov.. 1o, 4fsazz Patented Jan'. 6, 1925.

UNITED "STATES PATENT OFFICE.

JOHN E. GLICKERT, OF INDIANAPOLIS, INDIANA, ASSIGNOR T G & J' TIRE COMPANY,

or INDIANAroLIs, INDIANA,

A CORPORATION O'F INDIANA.

INNER TUBE AND ITS METHOD OF MANUFAGTURE.

Application led November 10, 1922. Serial No. 600,015.

To all 'whom t may concern.' A

Be it known that I, JOHN E. GLICKERT, a citizen of the United States, residing at Indianapolis, county of Marion, and State of Indiana, have invented a certain new and useful Inner Tube and its Method of Manufacture, of which the following is a full, clear, and exact description.

It has long been desirable to manufacture inner tubes with their valve stems pointing nearly exactly radially inward from thelr inner periphery. The methods heretofore in use have not admitted of properly controlling the disposition or inward direction 16 of extent ofthe valve stems, a greater percentagethan tolerable of the finished inner tubes having the valve stems canted to an objectionable extent from a true radial position. The present invention aims to obviate this diculty.

With the particular illustrated embod'i-` ment in mind and without intention to limitl more than is required by the prior art, the invention maybe said briefly to consist in separately rolling two sheets of stock around a ole and lapplng their margins so as to de ne two spaced-apart seams, ribs, or thickened zones, between which, a valve stem (and preferably also a reinforcing valve base therefor) may be located so that, when the tube is cured and nished, the valve stem projects radiall inward with suicient exactness to satis the trade.

An embodiment of the invention is illustrated in the accompanying drawings in which l Fig. 1 illustrates diagrammatically the successive steps in the preferred method of construction Fig. 2 represents a cross-section of al rolled tube taken through a valve base, and

Fig. 3 shows a cross-sectionl of a vulcanized and finished tube with the valve stem mounted in position therein..

According to my invention in its best practical form, asheetof stock 1, of the proper' length forthe size of tube in the making, is rolled about a straight pole, or other suitable arbor, 2, its sides or margins beinglapped, or otherwise seemed, as indicated at 3, to provide a rib or thickened portion.l The width of the sheet 1 is preferably such as to make one or more complete convolutions about the pole, one being preferable, as illustrated. This done, I preferably, but not necessarily, then apply a reinforcing valvey base 4 to the sheet of stock on the pole, desirably locating it with one` of its sides tangentially of the seam 3. The reinlforcing valve base, if used, may be of any suitable well-known construction, usually woven fabric cut on the bias is employed but recently cord fabric has been utilized. I then, preferably, coil a second sheet of stock 5 one or more times, preferably as shown only once, about the thus-formed pole, the width.of this second. sheet being preferably such as to permit forming a seam, rib, or thickened portion, 6 at the opposite side of the reinforcing valve base 4.

The thus-formed een or uncured tube is then cross-wrappe or otherwise prepared for vulcanization 1n a strai ht length on the ole 2. After being vulcanized, the straight en h of tube is then stripped from the pole an its ends joined together, preferably after buing or otherwise skiving them 0E, the necessary care being taken to bring the seamsl or thickened portions 3 and 6 into registration and on the inner periphery of the complete annular tube. A valve stem 7 is introduced in any convenient manner.

The article produced, as illustrated in Fig. 3 of the drawin s, has on its inner periphery symmetrically isposed seams, ribs, or thick,r ened portions, 8, whichin the finished tube that 1s usually, but not necessarily, turned* inside out before its ends are joined together-ribs, or thickened portions 8 tend, when the tube is infiated, to maintain their cured lengthy t least more than the main body of t e tu e, and thusto control the direction of extent of the valve stem that is anchored substantially midway between them. In Fig. 3, the correct osition of the valve stem is shown in soli lines and the incorrect,'or canted, ,position that was frequently found in old tubes is shown in dotted lines.

It willvbe obvious that the essential idea 10o of obtaining spaced-apart peripheral ribs or belts in the finished article may be accomplished in many other ways than by the two-sheet method of rolling above disclosed. In lieu of this method, preferred because of its practicality in a factory, the vulcanized rubber composition might be formed ,in a single sheet with a rib or thickened area at a suitable distance from one of its margins. Or two separately formed sheets might be superimposed so as to form a composite sheet, one ply inl thickness marginally, and two plies in thickness intermediately, such a composite orlaminated sheet being adapted to be handled like a single sheet and, when coiled about a pole, aording thickened portions or ribs as in the pure two sheet method. Or, one or more thin strips of rubber might be laid parallel upon a green tube that has already been coiled about a pole. Or, the stock might be tubed in a machine in one operation. These and other expedients'will be obvious to those skilled in the art as affording a way of accomplishing the end of '.the present invention, and all such are intended to be comprehended although not deemed as desirable as the two-sheet method disclosed in detail.

It is highly desirable, if not indispensable, to secure the valve stem to the tube midway between the ribs or thickened portions 8. It ls immaterial whetherl these portions 8 project from the outside or the inside of the finished tube, if, indeed, they may be f said to project at all noticeably. It is also immaterial whether or not the fabric valve base is employed. Practically, however, such a base is usually incorporated .in the tube leither intermediate its faces or plastered externally on one of them. The two ribs or thickened portions 8 may be spaced apart any desired extent. The angle thetwo ribs make withthe axis of the tube, considered as points, is best kept between 90 and 135. For auto tube sizes (5 inch and under) an angle of 120 seems most effective, while for truck sizes (v6 inch and jup) the most effective angle is between 90 and 105. But. no one angle is essential. To facilitate manufacture, and

particularly the incorporation of the valve base, the spacing of the thickened portions 8 may, therefore, be varied in different tubes and as conditions may dictate. The thickened portions 8 are preferably complete annuli, but `some measure ofcontrol of the valve stem may be effected by4 making them only a'fraction of the total innerperiphery of the tube. For ease in manufacture and the best results known, I prefer the two-sheet method detailed above.

In the claims, the expression vulcanized rubber composition is used to define compounded rubber and to exclude a rubber composition applied to a ply or -plies of fabric detracting from or otherwise modifying the elasticity or distensibility of the vulcanized rubber itself.

It will be understood that the present invention, both as to the article and the method, is not necessarily limited to particulars above disclosed and that for an understanding of the scope and breadth of the invention, reference should be made to the accompanying claims. i

Having thus described my invention, what I claim and .desire to protect by Letters Patent is:

1. An inflatable inner tube of vulcanized rubber composition having circumferentially extending and spaced-apart thickened portions for controlling lthe position of its valve stem.

2. An inner tube of vulcanized rubber composition having spaced-apart portions resisting change in their length on inflation more than the body portion of the tube, and a valve mounted between said spaced-apart portions, the position of whose stems is controlled .by said spaced-apart portions.

3. An inner tube of vulcanized rubber composition having annular spaced-apart thickened portions, and a valve stem secured thereto midway between and constrained t0 point radially inward by said thickened portions.

4. An inner tube of vulcanized rubber composition having a reinforcing valve base incorporated therein, thickened annular portions located on the inner periphery ofI the tube and symmetrically on .opposite sides of saidvalve base, and a valve secured to said inner tube centrally of the valvebase, the stem of the valve being constrained to point radially inward by said thickened annular portions.

5. An inner tube for pneumatic tire casings comprising, an annular tubular body of vulcanized rubber composition, a valve for inllating the same, and circumferentially extendingmeans united to the body and locatedsubstantially equal distances on opposite sides of the valve for controlling the direction of the valve stems projection.

6. That method of manufacturing inner tubes which includes, successively ceiling separate sheets of vulcanizable rubber composition about a pole with the sides of each sheet `overlapping on substantially parallel lines spaced apart circumferentially of the pole, incorporating a valve base in the vulcanizable rubber composition `and substantially symmetrical with relation to the seams formed in the respective overlaps, and vulcanizinQg-the tube thereby to form means for cbntrolling the position of and seaming its margins together, applying a reinforcing valve base to the coat on the pole and approximately tangent said seam, then rollinga second sheet of vuloaniZab-le rubber composition around the thus-covered pole and seaming its margins together at the opposite sides of and .substantially tangent to the reinforcing valve base,` subsequently curing the tube on the pole and joining its ends to form -a oomplete annular tube.

Signed at Indianapolis, county of Marion, andState of Indiana, this 2nd day of .November, 1922. v

JOHN E. GLICKERT. 

